(Press-News.org) With the "green" reputation of large hydroelectric dams already in question, scientists are reporting that millions of smaller dams on rivers around the world make an important contribution to the greenhouse gases linked to global climate change. Their study, showing that more methane than previously believed bubbles out of the water behind small dams, appears in ACS' journal Environmental Science & Technology.
Andreas Maeck and colleagues point out that the large reservoirs of water behind the world's 50,000 large dams are a known source of methane. Like carbon dioxide, methane is one of the greenhouse gases, which trap heat near Earth's surface and contribute to global warming. Methane, however, has a warming effect 25 times more powerful than carbon dioxide. The methane comes from organic matter in the sediments that accumulate behind dams.
That knowledge led to questions about hydroelectric power's image as a green and nonpolluting energy source. Maeck's team decided to take a look at methane releases from the water impoundments behind smaller dams that store water less than 50 feet deep.
They describe analysis of methane release from water impounded behind six small dams on a European river. "Our results suggest that sedimentation-driven methane emissions from dammed river hot spot sites can potentially increase global freshwater emissions by up to 7 percent," said the report. It noted that such emissions are likely to increase due to a boom in dam construction fostered by the quest for new energy sources and water shortages.
###
The authors acknowledge funding from the German Research Foundation.
The American Chemical Society is a nonprofit organization chartered by the U.S. Congress. With more than 163,000 members, ACS is the world's largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.
To automatically receive news releases from the American Chemical Society, contact newsroom@acs.org.
Follow us: Twitter Facebook END
Sediment trapped behind dams makes them 'hot spots' for greenhouse gas emissions
2013-07-31
ELSE PRESS RELEASES FROM THIS DATE:
Study offers promising new direction for organ regeneration and tissue repair
2013-07-31
BOSTON – Because most human tissues do not regenerate spontaneously, advances in tissue repair and organ regeneration could benefit many patients with a wide variety of medical conditions.
Now a research team led by investigators at Beth Israel Deaconess Medical Center (BIDMC) and Dana-Farber/Boston Children's Cancer and Blood Disorders Center has identified an entirely new approach to enhance normal tissue growth, a finding that could have widespread therapeutic applications.
Their findings were published on-line this week in the Proceedings of the National Academy ...
Chemical company giants stall with global economy
2013-07-31
The world's 50 largest chemical companies — with combined 2012 sales of almost $1 trillion and products that touch the lives of people everywhere — are the topic of the cover story in the current edition of Chemical & Engineering News. C&EN is the weekly newsmagazine of the American Chemical Society, the world's largest scientific society.
In C&EN's annual snapshot of the sales, profits, R&D spending and other indicators, Senior Correspondent Alexander Tullo points out that the Asian and Middle Eastern juggernauts that shot up the top 50 rankings during the past decade ...
New poll shows minority populations support clinical trials to improve health of others
2013-07-31
ALEXANDRIA, Va.—July 31, 2013—Altruism is a strong motivating factor for clinical trial participation in the general population and even more so among several minority groups. A significant percentage of African-Americans (61%), Hispanics (57%) and Asians (50%) say it's very important to participate as a volunteer in a clinical trial to improve the health of others, compared to 47% of non-Hispanic whites, according to a new national public opinion poll commissioned by Research!America.
These findings are tempered by the reality that participation remains disturbingly ...
3-D molecular syringes
2013-07-31
This news release is available in German. Abdominal pain, fever, diarrhoea -- these symptoms could point to an infection with the bacterium Yersinia. The bacterium's pathogenic potential is based on a syringe-like injection apparatus called injectisome. For the first time, an international team of researchers including scientists at the Helmholtz Centre for Infection Research (HZI) in Braunschweig, Germany, has unraveled this molecular syringe's spatial conformation. The researchers were able to demonstrate that the length of Yersinia's injectisome's basal body, which ...
VCU physicists discover theoretical possibility of large, hollow magnetic cage molecules
2013-07-31
Virginia Commonwealth University researchers have discovered, in theory, the possibility of creating large, hollow magnetic cage molecules that could one day be used in medicine as a drug delivery system to non-invasively treat tumors, and in other emerging technologies.
Approximately 25 years ago, scientists first made the discovery of C60 fullerene – better known as the Buckminster Fullerene – a molecule composed of 60 carbon molecules that formed a hollow cage. Due to its unique hollow cage structure the molecule offers serious technological potential because it could ...
Tiny, brightly shining silicon crystals could be safe for deep-tissue imaging
2013-07-31
BUFFALO, N.Y. — Tiny silicon crystals caused no health problems in monkeys three months after large doses were injected, marking a step forward in the quest to bring such materials into clinics as biomedical imaging agents, according to a new study.
The findings, published online July 10 in the journal ACS Nano, suggest that the silicon nanocrystals, known as quantum dots, may be a safe tool for diagnostic imaging in humans. The nanocrystals absorb and emit light in the near-infrared part of the spectrum, a quality that makes them ideal for seeing deeper into tissue ...
Robots strike fear in the hearts of fish
2013-07-31
Brooklyn, N.Y.—The latest in a series of experiments testing the ability of robots to influence live animals shows that bio-inspired robots can not only elicit fear in zebrafish, but that this reaction can be modulated by alcohol. These findings may pave the way for new methodologies for understanding anxiety and other emotions, as well as substances that alter them.
Maurizio Porfiri, associate professor of mechanical and aerospace engineering at the Polytechnic Institute of New York University (NYU-Poly) and Simone Macrì, a collaborator at the Istituto Superiore di Sanità ...
First experimental signs of a New Physics beyond the Standard Model
2013-07-31
The Standard Model, which has given the most complete explanation up to now of the universe, has gaps, and is unable to explain phenomena like dark matter or gravitational interaction between particles. Physicists are therefore seeking a more fundamental theory that they call "New Physics", but up to now there has been no direct proof of its existence, only indirect observation of dark matter, as deduced, among other things, from the movement of the galaxies.
A team of physicists formed by the professor of Physics at Universitat Autònoma de Barcelona (UAB) Joaquim Matias, ...
Key factors for wireless power transfer
2013-07-31
WASHINGTON D.C., July 31, 2013 -- What happens to a resonant wireless power transfer system in the presence of complex electromagnetic environments, such as metal plates? A team of researchers explored the influences at play in this type of situation, and they describe in the American Institute of Physics' journal AIP Advances how efficient wireless power transfer can indeed be achieved in the presence of metal plates.
The team discovered that resonance frequency matching, alignment of the magnetic field, and impedance matching are the most important factors for efficient ...
Binding together repelling atoms
2013-07-31
Basic chemistry tells us that a bond between atoms can form if it is energetically more favorable for the atoms to stick together than staying apart. This fundamentally requires an attractive force between the atoms. However, new theoretical predictions show that the combination of a repelling force and controlled noise from an environment can also have the surprising effect of leading to a bound state, although one with quite exotic properties. The research team consisting of Harvard postdoc Mikhail Lemeshko and former Harvard postdoc Hendrik Weimer* report their results ...